There is a growing interest in the role of LCOs and compositions thereof for enhancement of plant seed germination, seedling emergence and growth of plants both for crop and horticultural purposes in both legumes and non-legumes. Compositions for accelerating seed germination and plant growth are provided in Application No. PCT/CA99/00666, published Feb. 3, 2000, WO 00/04778, all contents of which are incorporated herein by reference. There is also an interest in the possible effects of LCOs in plant photosynthesis and PCT/CA00/01192, published Apr. 19, 2001, WO 01/26465 A1 describes the use of LCOs and compositions of LCOs for increasing plant photosynthesis. Chemical structures of LCOs are described in U.S. Pat. Nos. 5,175,149; 5,321,011 and 5,549,718. Synthetic LCOs are also known.
There is great interest in the field of agricultural research, particularly in the field of plant growth promoters, of plant physiological processes which may be affected by LCOs. Prithiviraj et al, Planta (2003) 216:437-445 discuss certain observed induced physiological changes in both host and non-host plants by LCOs, all contents of which is incorporated herein by reference.
LCOs are known to be released by Rhizobia, symbiotic bacteria primarily of the genera Generarhizobium, Bradyrhizobium, Sinorhizobium, Mesorhizobium and Azorhizobium and the like, the Rhizobiacese family being in a state of taxonomic flux Both of the aforesaid International applications summarize current understanding of the specialized symbiotic relationship of Rhizobia with legume host plants in the formation of nodule organs and associated fixation of atmospheric nitrogen within these organs, as well as the plant to bacteria signal and bacteria to plant signal interaction associated with such symbiotic relationship.
Although there is a considerable body of knowledge on the influence of LCOs on typical host plant physiology, there is a growing interest in the effect of LCOs on plant growth with respect to both host and non-host plants, particularly by application of the molecule without necessarily the fostering of a micro-organism and plants symbiotic relationship.
The body of knowledge relating to the possible role of LCOs, in both host and non-host plants and on processes associated with plant growth promotion continues to grow, with particular practical interest in the effects of LCOs on plant physiology and processes relevant to increase plant yields, not only with respect to commonly considered crop plants, both host and non-host, but also with respect to horticulture species.
Thus, there continues to be a need to study the effects of LCOs on plant growth, in addition to processes relating to nodulation and nitrogen fixation in legume host plants and to germination, emergence and photostimulation in both legume and non-legume plants. In particular, there is a need to study the effect of LCOs on bud and flowering initiation, budding, fruiting initiation and development, generally in relation to growth and maturity of plants, both leguminous and non-leguminous and the affect on plant yields. The present invention endeavours to address these and other needs.